1. Field of the Invention
The present invention relates to a chemical mechanical apparatus, and in particular to a conditioner cleaning device incorporating a chemical mechanical polishing pad. The conditioner cleaning device of the present invention is capable of increasing cleaning efficiency by uniformly spraying a cleaning solution on upper and side faces of a diamond disk. When the diamond disk is efficiently cleaned, the process reliability of a wafer is increased.
2. Description of the Related Art
In general, chemical mechanical polishing (CMP) is a technique that chemically and mechanically polishes the interlayer insulation layers typically formed on a wafer substrate during the fabrication of semiconductor devices. Interlayer insulation layers are used to cover wires in order to realize a satisfactory multiple wiring structure within the overall structure of a semiconductor device.
In order to fabricate a highly integrated semiconductor device having circuit lines with fine line width in a multistage layer, a high level polishing technique for surface planarizations is required. That is, in fabricating a densely-integrated semiconductor device there is a limitation to the use of mechanical surface polishing for ultra precision surfaces, i.e., below about 1 μm; thus, the CMP technique using both the chemical and mechanical polishing is currently used.
Recently, sub-micron processing below about 0.35 μm, requires a more detailed planarization technique to realize a fine pattern formation. In addition, continued development in the CMP technique is actively being sought and applied to next-generation semiconductor devices. The current CMP technique is often applied to logic-type devices requiring multiple layer wiring to realize high speed devices, but the use of multiple layer wiring in emerging memory devices has gradually increased.
The planarization of a wafer is performed in such a way that a non-polishing face of the wafer is held to a carrier head by vacuum pressure, and under this condition, a polishing face of the wafer is placed in contact with a polishing pad. While the polishing pad rotates, slurry is supplied between the polishing pad and the polishing face of the wafer.
In some additional detail, a CMP apparatus generally includes loadlock to load/unload a cassette, polishing unit, cleaning unit, and robot to transfer wafers therebetween.
As shown in FIG. 1, polishing unit for chemical mechanical polishing a wafer includes table 1, a plurality of platens (not shown), polishing pad 2, Head Cup Load Unload (HCLU) 3, and carrier (not shown). Polishing pad 2 is adapted to interlockingly operate on the upper face of platen. HCLU 3 is provided at a position where the wafer is loaded and unloaded by robot together with polishing pad 2. Polishing head 4, together with polishing pad 2, and HCLU 3 are each adapted to rotate on the upper portion of table 1.
While the wafer held to polishing head 4 is rotated with a uniform pressure in the same direction to one side of polishing pad 2, the wafer is polished mechanically by a friction force between polishing pad 2 and the wafer. Simultaneously, slurry is supplied onto an upper face of polishing pad 2 through slurry arm 5, which is provided at one end of polishing pad 2 to thereby planarize the wafer.
This polishing process requires continual maintenance of polishing pad 2. Thus, pad conditioner 6 is used to condition, i.e., maintain, the polishing pad.
As shown in FIG. 2 pad conditioner 6 is used to appropriately condition polishing pad 2 through the use of diamond disk 6a provided at one end thereof so as to even out the roughness of polishing pad's surface. Accordingly, a conditioning is applied to physically return polishing pad 2 to its original state. In this manner, the uniform surface level of polishing pad 2 is maintained, thereby maintaining a uniform pressure between polishing pad 2 and polishing head 4.
Unfortunately, some of the slurry used to chemically polish wafer W (shown in FIG. 2) may be absorbed onto the diamond disk 6a and solidified thereon. The solidified slurry may thereafter drop onto polishing pad 2, scratching its polishing face. A scratch on polishing pad 2 may damage the wafer being processed in the polishing apparatus. To prevent the generation of scratches and other damage to the wafer, cleaning device 7 adapted to clean diamond disk 6a is provided at a separate location wherein pad conditioner 6 may be cleaned.
As shown in FIG. 3, cleaning device 7 comprises cup housing 710 having a recess with a predetermined depth to form cleaning solution storing section 711. On cleaning solution storing section 711 an air bubble plate 720 is located therein. Cup housing 710 should have a diameter no smaller than the diameter of diamond disk 6a. Also, first nozzle 730 is provided on one side of cleaning solution storing section 711 to fill cleaning solution storing section 711 with a cleaning solution, such as DI water; and second nozzle 740 is provided proximate first nozzle 730 and within cleaning solution storing section 711 in such a way that the end tip portion of second nozzle 740 is positioned at a predetermined height.
A cleaning solution provided through first nozzle 730 fills to a certain level in cleaning solution storing section 711, and then the polishing face of diamond disk 6a pad conditioner 6 is lowered into the cleaning solution. At this time, air bubbles are generated from air bubble plate 720 to dislodge any foreign-substances adhering to the polishing face, particularly, solidified slurries. At the same time, a cleaning solution is sprayed via second nozzle 740 onto the upper surface of diamond disk 6a to remove and dislodge any foreign substances adhering to the upper section thereof.
However, in the conventional cleaning device 7, cleaning operation provided by second nozzle 740 is insufficient, thus even after the cleaning operation, foreign substances may remain on diamond disk 6a, which may damage a wafer being processed and thereby seriously lower the reliability of the semiconductor devices being formed on the wafer.
Accordingly, it is desirable to provide a conditioner cleaning apparatus for a chemical mechanical polishing pad capable of preventing scratches and damages on wafers caused by solidified slurries. It is also desirable to provide a conditioner cleaning apparatus capable of efficiently cleaning a diamond disk.